I agree that disruption is the other major threat, which they also pour billions into via acquisitions and VC activities. My guess though is that the possibility of govt action is what really scares them, and most of the tech elite. You can tell when Google realised this by noting that they went from spending almost nothing on lobbying to spending quite a lot (coinciding roughly with their transition from “don’t be evil” to “c’mon, man, be real “)

It’s not that long ago that Microsoft was facing the very real possibility of antitrust, so it’s very much something leaders of tech companies have a duty (to shareholders) to defend against.